1. Field of the Invention
The invention relates to the testing of interface logic in a data processing system, and more particularly to a firmware/hardware method of testing interface logic without dismantling the processing system or using specialized attachments to provide return signals.
2. Prior Art
Diagnostic testing of data processing systems heretofore has required return cycle responses from system units other than the unit to be tested, the attachment of specially designed diagnostic test units to the system, or the detachment of a system unit from the processing system for isolated testing. No satisfactory means has been provided for testing through an interface in an operational environment, and isolating the test results from errors induced by the interface logic of system units not under test.
The present invention is directed to a method and system for testing the interface logic of system units intercommunicating by way of a common bus. The system under test need not be detached from the processing system, nor integrated with special diagnostic equipments. Rather, the system unit under test may be isolated from errors occuring in the interface logic associated with other system units without altering the system configuration.